Adjustment of the Speed of a Motor Vehicle with an Automatic Gearbox

ABSTRACT

A method relieves the burden of a driver of a motor vehicle in which the drive train is provided with a gearbox which can be operated in an automatic mode and a manual mode. The method comprises the following automatic steps: a) detection whether the speed of the vehicle should be adjusted, b) initiation of the adjustment if necessary, and c) the carrying out of the adjustment. During step b) and/or step c) it is determined on one or several occasions whether the gearbox is operating in an automatic mode or in a manual mode in order to trigger a change into the automatic mode of the gearbox if the gearbox is operated in the manual mode.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/793,060 filed Mar. 4, 2004; which is a continuation of copendingInternational Application No. PCT/DE02/03298 filed Sep. 6, 2002 whichdesignates the United States, and claims priority to German applicationno. 101 43 735.8 filed Sep. 6, 2001; the contents of which areincorporated herein by reference in their entirety.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a method for relieving the burden of a driverof a motor vehicle in which the drive train is provided with a gearboxthat can be operated in an automatic mode and a manual mode. Such amethod comprises the following automatic steps:

a) detection whether the speed of the vehicle should be adjusted,

b) initiation of the adjustment of the speed of the vehicle, ifnecessary, and

c) carrying out the adjustment of the speed of the vehicle.

The invention also relates to a device for initiating and carrying outan automatic speed adjustment of a motor vehicle in which the drivetrain is provided with a gearbox that can be operated in an automaticmode and a manual mode.

DESCRIPTION OF THE RELATED ART

These kinds of methods and devices were developed with the objectivetarget to relieve the burden of a driver of a motor vehicle from all thetasks by means of suitable auxiliary means and in this way to improvethe overall ride comfort in which case these kinds of devices aregenerally referred to as “cruise control”. The object of the cruisecontrol device is to maintain the speed entered on the part of thedriver. Relieving the burden of a driver is based on the fact that thedriver to a large extent does not have to intervene to maintain aconstant driving speed. The cruise control compensates bycorrespondingly engaging the drive train of the motor vehicle forinfluences affecting and changing the speed such as road inclination,frictional resistance, vehicle loading, etc. The efficiency of thecruise control particularly depends on the torque characteristics of theengine and/or additional drive sources (for example, additional electricmotors, starter generators, etc.), the gearbox concept used (automaticor non-automatic gearbox), manual or automatic brake initiation andother auxiliary means that can for example be used to detect obstacles(distance) lying in the direction of travel and their state of movement.

In addition to maintaining the constant speed specified by the driver bymeans of suitable engine and/or gearbox engagement, several cruisecontrols offer a series of additional functions. For example, the driverin the case of some embodiments can specify a desired maximum speed. Inthis way, the cruise control limits the wheel moment by means of engineand/or gearbox engagements in such a way that the desired maximum speedis not exceeded. In addition, there already are solutions in which thedriver can increase or reduce the desired set speed without having toactuate the accelerator pedal preferably within the specified limits byactuating the corresponding operating elements of the cruise control.For several embodiments, the cruise control can reduce the speed in asuitable way on detecting an obstacle, for example, a preceding motorvehicle for which an automatic brake initiation is carried out, ifrequired, and thereafter the original set value is once again restored.

Cruise controls are very often offered together with automatic gearboxesbecause an engine engagement is often not enough to keep the desiredspeed constant, for example in the case of inclinations, and the desiredspeed can only be achieved by using a parallel change in thetransmission ratio. Cruise controls are offered particularly to enginesthat can provide a relatively high torque, but they are alsoincreasingly being offered to non-automatic gearboxes (standard manualgearboxes). Here, the desired speed can only be adjusted by changing thetorque of the engine because an automatic gearbox engagement is notpossible. This results in the fact that the effective range of thecruise control is more limited than in vehicles with automaticgearboxes. Should the desired speed for example be changed via thecruise control, the speeds corresponding to the engaged transmissionratio step are available as physical limits that result from the extremespeed values of the engine, i.e. from the idling and cutoff speed. Onlythe driver can adjust a desired speed lying outside this range bymanually changing the transmission ratio.

In addition to automatic gearboxes and standard manual gearboxes,so-called automatic manual gearboxes are also used in the meantime. Suchautomatic manual gearboxes automate the standard manual gearboxes byautomatically actuating the clutch and the gearbox. The automatic manualgearboxes can be operated both in a manual mode by the driver himselfmaking decisions regarding the selection of the transmission ratio bymanual engagements (by touching a plus/minus gearshift lever) or in anautomatic mode where the transmission ratio is selected automatically,for example, by accessing logged switching characteristics, particularlytogether with driving strategy information.

From the literature DE 199 26 693 A1, a method for the manualtransmission ratio specification of a continuously variable transmissionof a motor vehicle is well-known. The gearbox can then be operated bothin an automatic and in a manual operating mode. In the manual operatingmode, a signal that is proportional to the speed of the motor vehicle isspecified as the setpoint specification for the operating point guide ofthe manual gearbox unit.

SUMMARY OF THE INVENTION

The object of the invention is to further develop these kinds of methodsand devices in such a way that their efficiency is amplified whencompared to the state of the art explained above.

This object of the invention can be solved by a method for relieving theburden of a driver of a motor vehicle in which the drive train isprovided with an automatic gearbox that can be operated in a manual modeand an automatic mode in which the transmission ratio is changedautomatically comprising the following steps:

a) detecting whether the speed of the vehicle should be adjusted,

b) initiating of the adjustment of the speed of the vehicle, ifnecessary, and

c) carrying out the adjustment of the speed of the vehicle,

wherein on carrying out step b) and/or the step c), it is determined onone or several occasions whether the gearbox is operating in anautomatic mode or in a manual mode in order to trigger a change into theautomatic mode of the gearbox if the gearbox is operated in the manualmode.

On carrying out step b) and/or step c) it can be determined on one orseveral occasions whether changing the transmission ratio of the gearboxis advantageous and that a change into the automatic mode is onlytriggered if changing the transmission ratio of the gearbox isadvantageous. Triggering the change into the automatic mode of thegearbox may take place by outputting a signal to the driver that heshould manually change the gearbox into the automatic mode. Triggeringthe change into the automatic mode of the gearbox may also take place byactivating a gearbox control and/or adjustment in such a way that itautomatically carries out the change. When starting the execution ofstep b), the mode in which the gearbox is operated at the moment can bestored. After executing step c), operation of the gearbox in the storedmode can be ensured. Step c) may be terminated automatically if thedriver has activated the manual mode of the gearbox. Step a) may includethat it is monitored whether or not the driver more or less keeps ortries to keep the speed constant. Step b) and/or step c) may include theonce only or repeated detection of a setpoint speed. On executing stepc) by engaging the drive train and/or other components of the motorvehicle, the real speed of the motor vehicle may track the setpointspeed and for this an acceleration pattern may be used that is selectedfrom several different acceleration patterns. The driver can select theused acceleration pattern. The used acceleration pattern can be selectedon the basis of information gained during the distance covered by thedriving operation. On executing step b), the distance to and/or thespeed of possible obstacles can to be taken into consideration. Thedrive train may have several components that can output and/or recordpower and that the execution of step c) includes the effect on one orseveral of these components. The execution of step c) can take place onthe basis of the wheel moment.

A motor vehicle may comprise a drive train, an automatic gearbox coupledwith the drive train that can be operated in a manual mode and anautomatic mode in which the transmission ratio is changed automatically,an automatic speed adjustment unit coupled with said gearbox, a controldevice coupled with said automatic gearbox and said automatic speedadjustment unit, wherein the control device comprises means to detectthe activation of the automatic speed adjustment unit, and switchingmeans to switch from the manual mode to the automatic mode of theautomatic gearbox, wherein the switching means are controlled if theautomatic speed adjustment is active and the automatic gearbox is inmanual mode.

The control device may control the transmission ratio of the gearbox anddetermine during activation of the automatic speed adjustment unitwhether a change of the transmission ratio is advantageous and that achange into the automatic mode is only triggered if changing thetransmission ratio of the gearbox is advantageous. The control devicecan trigger the change into the automatic mode of the gearbox byoutputting a signal to the driver that the gearbox in the automatic modeshould be changed manually. The control device can trigger the change inthe automatic mode of the gearbox by activating a gearbox control and/oradjustment in such a way that it automatically carries out the change.On initiating the automatic speed adjustment, the mode in which thegearbox can be operated at the moment is stored. On ending the automaticspeed adjustment, the control unit may activate the gearbox controland/or adjustment in such a way that this ensures an operation of thegearbox in the stored mode. The control unit may end the automatic speedadjustment if the driver of the motor vehicle activates the manual modeof the gearbox. The control unit may initiate the automatic speedadjustment or offers to the driver of the motor vehicle the initiationof the automatic speed adjustment to more or less keep the speedconstant should it be detected that the driver more or less keeps ortries to keep the speed constant. On initiating and/or carrying out theautomatic speed adjustment, the control unit may detect the setpointspeed once only or repeatedly. The control unit can use an accelerationpattern to carry out the automatic speed adjustment that was selectedfrom several different stored acceleration patterns. The driver of themotor vehicle can select the used acceleration pattern. The usedacceleration pattern can be selected on the basis of information gainedduring the distance covered by the driving operation. On carrying outthe automatic speed adjustment, the distance to and/or the speed ofpossible obstacles can be taken into consideration. The drive train mayhave several components that can output and/or record power and that oncarrying out the automatic speed adjustment, it directly or indirectlyhas an effect on one or several of these components. Automatic speedadjustment can be carried out on the basis of the wheel moment.

The method according to the invention for relieving the burden of adriver of a motor vehicle is provided according to the state of the artbecause during step b) and/or the step c) it is determined on one orseveral occasions whether the gearbox is operating in an automatic modeor in a manual mode in order to trigger a change into the automatic modeof the gearbox if the gearbox is operated in the manual mode. The term“manual mode” means that the driver changes the gear by for exampleactuating a touch key (manual). However, the clutch need not be actuatedto change the gear because these functions are taken over by the clutchor gearbox actuator. In contrast to this, all the gear changes aretriggered automatically in the “automatic mode”, i.e. engagement by thedriver for example via the touch key is not necessary here. The solutionaccording to the invention amplifies the efficiency when compared to thestate of the art because after changing to the automatic mode, theinitially mentioned physical limits for the reachable desired speed areno longer limited to the speeds corresponding to an engaged transmissionratio step. An optimized speed adjustment can be carried out in theautomatic mode because in addition to the engine torque engagements itis also possible to select transmission ratio engagements.

An advantageous further development of the method according to theinvention provides that during step b) and/or step c) it is determinedon one or several occasions whether changing the transmission ratio ofthe gearbox is advantageous and that a change into the automatic mode isonly triggered if changing the transmission ratio of the gearbox isadvantageous. For example, it is feasible that the driver whiletraveling on the highway in the manual mode of the gearbox has alreadyshifted to and engaged in the highest gear so that changing thetransmission ratio within relatively high setpoint speed ranges is notadvantageous. In this case, the gearbox can at least for the time beingbe operated further in the manual mode until there are considerable roadinclinations.

In the case of specific embodiments of the method according to theinvention it is provided that the change into the automatic mode of thegearbox is triggered by outputting a signal to the driver that thegearbox in the automatic mode should be changed manually orautomatically. Signaling takes place by means of suitable signalingdevices that can particularly be formed by optical and/or acousticsignaling devices.

Other embodiments of the method according to the invention provide thatthe change into the automatic mode of the gearbox is triggered byactivating a gearbox control and/or adjustment in such a way that itautomatically carries out the change. The automatic change can theneither always or only then be carried out if it was determined thatchanging the transmission ratio of the gearbox is advantageous.

Furthermore, in the case of all embodiments of the method according tothe invention it can be provided that when starting the execution ofstep b), the mode in which the gearbox is operated at the moment isstored.

In this context, an advantageous further development of the methodaccording to the invention provides that after executing step c),operation of the gearbox in the stored mode is ensured. In this caseafter the execution of step c) the gearbox is changed in the manual modeif this mode was active before the activation of the speed adjustmentwhereas on the other hand the automatic mode is retained.

An advantageous further development of the method according to theinvention provides that step c) ends automatically if the driver hasactivated the manual mode of the gearbox. This of course does notexclude the application of conventional exit conditions such as brakepedal actuation, accelerator pedal actuation, etc.

A preferred embodiment of the method according to the invention alsoprovides that step a) includes that it is monitored whether or not thedriver more or less keeps or tries to keep the speed constant. Providedthat it was determined that the driver more or less keeps or tries tokeep the speed constant, an optical and/or acoustic signal can forexample be generated that offers a speed adjustment to the driver.

The method according to the invention preferably also provides that stepb) and/or step c) includes the once only or repeated detection of asetpoint speed. For example, the current real speed can be taken over byactuating a key or suchlike as the setpoint speed. However, the setpointspeed can also be detected independent of the real speed. If the driver,for example, provides a setpoint speed for a stationery motor vehicle,the vehicle can be accelerated to the envisaged speed after the brakecontrol has automatically been released by suitable engagements in theengine and gearbox control or adjustment. For this, an automatictransition from the stationery vehicle via a pulling away process up toswitching processes including engine engagements is provided.

A preferred further development of the method according to the inventionprovides that on executing step c) by engaging the drive train and/orother components of the motor vehicle, the real speed of the motorvehicle tracks the setpoint speed and that for this an accelerationpattern is used that is selected from several different accelerationpatterns. The drive train can have more than one driving motor in thesame way as all the embodiments of this invention. For example, aninternal combustion engine can be provided with an associated startergenerator in which case the latter can also be used to drive the motorvehicle. For example, it is feasible that for low setpoint speeds onlyan electric motor should be used for the drive. The other components ofthe vehicle can particularly include the braking system without beinglimited to it. When converting from conventional acceleration processeswithout speed adjustment, the actuation of the accelerator pedal isusually evaluated. The accelerator pedal information, for example, thedeflection of the accelerator pedal and/or the accelerator pedalgradient is then, on the part of the engine control and/or adjustment orwhen switching on the part of the gearbox control, converted to acorresponding desired engine torque. However, in the case of speedadjustment, i.e. acceleration to the setpoint speed, such acceleratorpedal information is usually not available. In order to close this gap,several different acceleration patterns are provided in the preferredembodiment of the invention of which at least one is used to track thereal speed. In a simple case, the different acceleration patterns can beformed by a slow, an average and a quick acceleration. It is alsofeasible that the acceleration patterns be further adapted to the motorvehicle load, the road inclination, road course, driver type, a wheelslip recognition, etc. Adjusting the desired acceleration pattern or thedesired acceleration dynamics can also be carried out by adjusting acustomary-implemented cruise control, for example, a PID control or thelike in the cruise control.

In this context, the method according to the invention can provide thatthe driver can select the used acceleration pattern. It is, for example,possible that the driver under acceleration patterns for a slow, anaverage and a quick acceleration, selects the acceleration pattern to beused.

In addition or alternatively the method according to the invention canprovide that the used acceleration pattern can be selected on the basisof information gained during the distance covered by the drivingoperation. It is already known that driver-specific variables, forexample a sporty or comfort-accentuated ride must be determined and thisinformation should for example be used for switching transition control.The same or similar information can be used for determining and/orselecting acceleration patterns.

An advantageous further development of the method according to theinvention provides that on executing step b) the distance to and/or thespeed of possible obstacles is to be taken into consideration. Obstaclescan be both stationery obstacles and obstacles moving around on the roadand/or on the edge of the road, for example around advancing vehicles.In order to face up to potential hazardous situations in a suitablemanner, the speed adjustment also in this context preferably allowsautomatic brake initiations. The delay dynamics can for example beadapted to the current driving situation to guarantee asituation-equitable delay, i.e. for a great speed difference and a shortdistance to the obstacle ahead the delay dynamics should be high and, onthe other hand, for a slight speed difference and long distance low.

An advantageous further development of the method according to theinvention provides that the drive train has several components that canoutput and/or record power and that the execution of step c) includesthe effect on one or several of these components. Depending on whichcomponents are in the drive train, for example, the internal combustionengine, starter generator, electric motor, gearbox and combinations fromthis, a central decision can be made which drive train components areused to reach and/or hold the setpoint speed. This allows anefficiency-optimized drive train control both with regard to theconsumption and the comfort. As has already been mentioned above it isfeasible that only one electric motor be used in the case of low desiredspeeds or setpoint speeds.

A preferred embodiment of the method according to the invention alsoprovides that the execution of step c) takes place on the basis of thewheel moment. In this way, future developments concerning the drivetrain can also be taken into account and the drive train components canbe set to the optimum. In addition to the automatic speed adjustment andacceleration pattern used for this, this preferably also applies to theconventional driving operation.

Each device that is suitable for carrying out an embodiment of themethod according to the invention lies within the protective range ofthe associated claims.

The device according to the invention for initiating and carrying out anautomatic speed adjustment of a motor vehicle is provided according tothis kind of state of the art and is connected to a gearbox controland/or adjustment and provides that on initiating and/or carrying outthe automatic speed adjustment it is determined on one or severaloccasions whether the gearbox is operating in an automatic mode or in amanual mode in order to trigger a change into the automatic mode of thegearbox if the gearbox is operated in the manual mode. As a result theadvantages explained together with the method according to the inventionfollow in the same or in a similar way for which reason reference ismade to the corresponding embodiments in order to prevent repetitions.

Accordingly, the same applies to the following preferred embodiments ofthe device according to the invention in which case reference is alsomade to the corresponding embodiments together with the method accordingto the invention with regard to the advantages that can be obtained withthese embodiments.

Preferred embodiments of the device according to the invention providethat on initiating and/or carrying out the automatic speed adjustment itis determined on one or several occasions whether changing thetransmission ratio of the gearbox is advantageous and that a change intothe automatic mode is only triggered if changing the transmission ratioof the gearbox is advantageous.

Specific embodiments of the device according to the invention providethat it triggers the change into the automatic mode of the gearbox byoutputting a signal to the driver that the gearbox in the automatic modeshould be changed manually.

Other embodiments of the device according to the invention provide thatit triggers the change into the automatic mode of the gearbox byactivating a gearbox control and/or adjustment in such a way that itautomatically carries out the change.

Preferred embodiments of the device according to the invention alsoprovide that on initiating the automatic speed adjustment, the mode inwhich the gearbox is operated at the moment is stored.

Furthermore, in the same way as for the method according to theinvention, a preferred embodiment of the device according to theinvention is also provided in this context that on ending the automaticspeed adjustment, it activates the gearbox control and/or adjustment insuch a way that this ensures an operation of the gearbox in the storedmode.

Preferred embodiments of the device according to the invention providethat it ends the automatic speed adjustment if the driver of the motorvehicle activates the manual mode of the gearbox.

Furthermore, the device according to the invention can provide that itinitiates the automatic speed adjustment or offers to the driver of themotor vehicle the initiation of the automatic speed adjustment to moreor less keep the speed constant should it be detected that the drivermore or less keeps or tries to keep the speed constant.

Also a preferred further development of the device according to theinvention provides that on initiating and/or carrying out the automaticspeed adjustment, it detects the setpoint speed once only or repeatedly.

Specially preferred embodiments of the device according to the inventionprovide that it uses an acceleration pattern to carry out the automaticspeed adjustment that was selected from several different storedacceleration patterns.

In this context, the device according to the invention further providesthat the driver of the vehicle can select the used acceleration pattern.

In addition or alternatively, in this context the device according tothe invention can provide that the used acceleration pattern can beselected on the basis of information gained during the distance coveredby the driving operation.

In the same way as for the method according to the invention, anadvantageous further development of the device according to theinvention provides that on carrying out the automatic speed adjustment,the distance to and/or the speed of possible obstacles is to be takeninto consideration.

Furthermore, the device according to the invention provides that thedrive train has several components that can output and/or record powerand that on carrying out the automatic speed adjustment, it directly orindirectly has an effect on one or several of these components.

The device according to the invention also deems it advantageous if itis provided that automatic speed adjustment is carried out on the basisof the wheel moment.

The invention is based on the knowledge that it is possible to use thesynergies of cruise controls and automatic gearboxes with suitableconnections. The invention can be used in all automatic gearboxes. Insemi-automatic gearboxes at least some of the explained embodiments canbe implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will emerge from the descriptionwhich follows and from the accompanying drawings.

They are as follows:

FIG. 1 a flow chart that illustrates a relatively simple embodiment ofthe method according to the invention,

FIG. 2 a flow chart that illustrates an example of a speed adjustment onthe basis of the wheel moment,

FIG. 3 a block diagram that illustrates in a simplified way thecooperation of an embodiment of the device according to the inventionwith other components of a motor vehicle, and

FIG. 4 two graphs illustrating the relation between the setpoint wheelmoment curve and the speed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a flow chart that illustrates a relatively simple embodimentof the method according to the invention. The shown procedure startswith step S1. Step S2 detects whether or not an automatic adjustment ofthe speed of a motor vehicle should be carried out that corresponds tothe procedural step a). To this effect, the operating elements of thedevice according to the invention or a cruise control are requested in asuitable way. In addition, it is also possible to this effect to monitorwhether or not the driver of the motor vehicle more or less keeps thespeed constant or tries to more or less keep the speed constant. Shouldthis be the case, the driver can be requested to carry out the automaticspeed adjustment in a suitable way. Provided that an automatic speedadjustment should not be carried out, branch back to step S1. Providedthat it is determined in step S2 that an automatic speed adjustmentshould be carried out, branch to step S3. Step S3 detects the desired orsetpoint speed and the real speed. The setpoint speed can be detectedfor example while the current real speed is taken over by actuating anoperating element as the setpoint speed. In addition, it can also beprovided in this context that the driver determines the setpoint speedindependent of the current real speed in a suitable way. With regard toautomatic motor vehicle control systems it is also feasible thatexternal devices supply the setpoint speed. After the setpoint and realspeed were detected in step S3, proceed to step S4. Step S4 checkswhether or not a change in the gear transmission ratio is advantageous.To this effect, the real speed, the engine torque and the wheel momentsas well as the current gear transmission ratio can for example beevaluated. Provided that it is determined in step S4 that a change inthe gear transmission ratio is not advantageous, branch to S7 while thespeed adjustment explained in greater detail in FIG. 2 is carried outlater. If it is determined in step S4 that a change in the geartransmission ratio is advantageous, proceed to step S5. In step S5 acheck is performed to determine whether or not the gearbox is operatedin the manual mode or in the automatic mode. Provided that the gearboxis already operating in the automatic mode, branch to step S7 while thespeed adjustment is carried out. If the gearbox is operated in themanual mode, proceed to step S6 in which the automatic mode of thegearbox is activated. For the embodiment of the method according to theinvention shown in FIG. 1 it is assumed that the gearbox control oradjustment can automatically change the mode of the gearbox, i.e.without an engagement by the driver being necessary in this case. Theabove-mentioned steps S3 to S6 correspond to the procedural step b) interms of the embodiment of the method according to the invention shownin FIG. 1. After the automatic mode of the gearbox was activated in stepS6, proceed to step S7 in which the speed adjustment is carried out(procedural step c)) explained in greater detail in FIG. 2. In step S8 acheck is performed to determine whether or not the speed adjustmentshould end. Ending the speed adjustment can be called up by means ofdifferent abort criteria, for example by actuating an operating elementof the cruise control, actuating the brake pedal or also by externalinfluences with regard to the automatic control method. Provided thatthe automatic speed adjustment should end, branch back to step S1.Otherwise, branch back to step S3 in which the setpoint and real speedare redetected. At least when step S3 is carried out again, it can beprovided that the previous setpoint and real speed are taken overprovided that no engagement by the driver is necessary in this case.

FIG. 2 is a flow chart that illustrates an example of a speed adjustmenton the basis of the wheel moment. Carrying out the speed adjustment onthe basis of the wheel moment is advantageous because as a result themethod according to the invention (and also the device according to theinvention) can be adapted in a relatively simple way to design changesof the drive train. Step S71 determines the desired speed and a desiredacceleration curve. Therefore, the desired speed corresponds to thesetpoint speed that was already detected in step S3 shown in the FIG. 1.For example, the desired acceleration curve can be selected from manydifferent stored acceleration patterns. For example, the accelerationpatterns can be specified non-varying and/or determined on the basis ofinformation that was gained during the covered driving operation.Therefore, for example, a sporty or comfort-accentuated accelerationpattern adapted to the specific driver can be determined and/orselected. In step S72, the required wheel moment is calculated from thepreviously gained information. Subsequently, proceed to step S73 inwhich the control of the drive train is initiated. In the case of theembodiment shown in FIG. 2, the control of the drive train is carriedout by a drive train driver software active in step S74 that in steps 75a to 75 d acts on one or several drive train components AK1 to AKn in asuitable way. These drive train components AK1 to AKn can be for examplebe an internal combustion engine and/or an electric motor (for example,as a starter generator) and/or the gearbox and/or other components thatcan record and/or output power. After one or several drive traincomponents AK1 to AKn have been influenced in a suitable way, thedesired wheel moment is output in step S76.

FIG. 3 is a block diagram that illustrates in a simplified way thecooperation of an embodiment of the device according to the inventionwith other components of a motor vehicle in which case the shown deviceis also suitable for carrying out the method according to the invention.The embodiment shown in FIG. 3 includes a drive train 10 and an internalcombustion engine 20 to which internal combustion engine sensors andactuators 22 are allocated. A starter generator 16 is provided on theoutput shaft of the internal combustion engine 20 that is equipped witha starter generator control or adjustment 18. The output shaft of theinternal combustion engine 20 is also connected to the gearbox 12 thatcan be operated both in the manual mode and the automatic mode. Agearbox control or adjustment 14 is allocated to the gearbox 12. Thegearbox 12 is connected to at least one driving gear 34. In the case ofthe embodiment shown in FIG. 3, the device according to the invention isat least partially implemented in an engine control or adjustmentdesignated with 24. The engine control 24 is also connected to thecruise control operating elements 26 which according to conventionalmeans can consist of keys and/or levers and the like. Particularly inthe case of embodiments in which the driver can explicitly give asetpoint speed independent of the real speed it is preferred to thiseffect that suitable input devices are provided that for example allow akeyboard and/or voice input. The engine control 24 is also connected togearbox operating elements 28 that in the case of automatic manualgearboxes usually consist of at least two keys. For an automaticpedal-operated gearbox, the gearbox operating elements 28 must beadapted in a suitable way. FIG. 3 also shows an image processing unit 30that is designed to detect possible obstacles or the distance to themand, if required, their speed so that hazardous situations can beavoided, particularly while the speed adjustment suitably adapts to thesetpoint speed and with that to the real speed, if required, also via abrake initiation. In case the device according to the invention does notautomatically initiate the gearbox 12 via the gearbox control 14 tochange into the automatic mode should this be practical, a signalingdevice 32 is shown in FIG. 3. The signaling device 32 must then initiatethe change of the gearbox 12 into the automatic mode while the signalingdevice 32 generates an optical and/or acoustic signal that outputs asignal to the driver that a manual change of the gearbox 12 into theautomatic mode should be carried out via the gearbox operating elements28.

FIG. 4 shows two graphs that illustrate the connection between thesetpoint wheel moment curve (top graph) and the speed (bottom graph). Inthis case, curve K1 illustrates an acceleration pattern with a lowacceleration value, curve K2 an acceleration pattern with an averageacceleration value and curve K3 an acceleration pattern with a highacceleration value. The acceleration value illustrated by curve K1 canbe used for example to reach the setpoint speed if it was detectedbeforehand that the driver prefers a comfort-accentuated style ofdriving. The acceleration value illustrated by curve K3 can be used in asimilar way if it was detected that the driver prefers a sporty style ofdriving. In the bottom part of FIG. 4, curve K4 illustrates the speedcurve which follows if the acceleration pattern is used with the lowacceleration value illustrated by curve K1 in order to reach thesetpoint speed.

The features of the invention revealed in the above-mentioneddescription, the drawings and the claims can be of considerableimportance both individually or in any combination for the embodiment ofthe invention.

1. A method for relieving the burden of a driver of a motor vehicle inwhich the drive train is provided with an automatic gearbox that isoperated in a manual mode and can be switched into an automatic mode inwhich the transmission ratio is changed automatically comprising thefollowing steps: a) detecting whether the speed of the vehicle ismaintained within a speed range for a predetermined time period, b)indicating a possible switch into an automatic mode for said gearbox, c)switching the gearbox into automatic mode, d) detecting whether thespeed of the vehicle should be adjusted, e) initiating of the adjustmentof the speed of the vehicle, if necessary, and f) carrying out theadjustment of the speed of the vehicle.
 2. The method according to claim1, wherein step c) is only performed after the driver confirmed theswitch.
 3. The method according to claim 1, wherein step c) isautomatically performed after an evaluation of the gearbox ratio.
 4. Themethod according to claim 1, wherein triggering the change into theautomatic mode of the gearbox takes place by outputting a signal to thedriver that he should manually change the gearbox into the automaticmode.
 5. The method according to claim 1, wherein triggering the changeinto the automatic mode of the gearbox takes place by activating agearbox control and/or adjustment in such a way that it automaticallycarries out the change.
 6. The method according to claim 1, wherein,when starting the execution of step e), the mode in which the gearbox isoperated at the moment is stored.
 7. The method according to claim 6,wherein, after executing step f), operation of the gearbox in the storedmode is ensured.
 8. The method according to claim 1, wherein step f) isterminated automatically if the driver has activated the manual mode ofthe gearbox.
 9. The method according to claim 1, wherein step d)includes that it is monitored whether or not the driver keeps or triesto keep the speed constant.
 10. The method according to claim 1, whereinstep e) and/or step f) includes the once only or repeated detection of asetpoint speed.
 11. The method according to claim 10, wherein, onexecuting step f) by engaging the drive train and/or other components ofthe motor vehicle, the real speed of the motor vehicle tracks thesetpoint speed and for this an acceleration pattern is used that isselected from several different acceleration patterns.
 12. The methodaccording to claim 11, wherein the driver can select the usedacceleration pattern.
 13. The method according to claim 11, wherein aprevious driving operation is evaluated and the acceleration pattern isselected on the basis of this evaluation.
 14. The method according toclaim 1, wherein, on executing step e), the distance to and/or the speedof possible obstacles is evaluated.
 15. The method according to claim 1,wherein the drive train has several components that can output and/orreceive power and that the execution of step f) includes managing theeffect of output or received power on one or several of thesecomponents.
 16. The method according to claim 1, wherein the executionof step f) takes place on the basis of the wheel moment.